CGS064 VCA help!

[active]

i just finished building this little guy and have him all wired up. sounds fine, however the CV in seems to be acting a bit....weird. cv in does nothing at all while the cv invert sends the inverted CV signal to the circuit, but then returns to full on once the release has gone. i can send pictures if that will help but i really don't know how to trace down the CV in. all the contacts are right as to the diagram on the CGS website and all solder joints are solid and tested. any ideas?

[Mongo1]

Hi,

So it sounds like you need to start with the control voltage input stage.

If you have a voltmeter, you should verify that the power is getting to that op amp. If so, you can then check the output (pin 7) of that first control voltage op-amp. With no inputs, can you adjust the value of the CV Init Preset pot, and see if the pin 7 output moves as expected? If not, there's something wrong with the amp circuit. If you have equipped Initial Gain pot, you should also be able to see the opamp output change when you adjust that pot.

Remember that that stage is inverting, so the output should move in the opposite direction as the wiper on the pot.

Also be sure and follow the setup instructions for that module on the CGS site.

See how that works and we can go from there.

[active]

got it. i forgot the jumper between the transistors.

at least i now have my first working VCA!!!